Big regional differences in glaucoma diagnosis found

NEW YORK (Reuters Health) - A new analysis of Medicare records finds dramatic differences across the U.S. in rates of new glaucoma diagnoses, suggesting the eye disease is likely being overdiagnosed in some regions and underdiagnosed in others, researchers said.

Looking at all Medicare claims for a seven-year period, the team found glaucoma rates had risen slightly overall, but that people in New England or the Mid-Atlantic states had about 30 percent higher odds than people in the Southeast of being diagnosed with glaucoma -- and some 70 percent higher chances of getting a suspected-glaucoma diagnosis.

"We're seeing that potentially both physicians and patients in (predominantly rural) areas are not getting the healthcare that would be obtained in a large urban setting," such as the New York-Baltimore-Philadelphia area, said Dr. Harry Quigley, a professor of ophthalmology at Johns Hopkins University School of Medicine who worked on the study.

The findings are published in the journal Ophthalmology.

Lower diagnosis rates in less-urbanized settings may stem from different physician styles in examining patients and detecting glaucoma or fewer eye-care visits by patients, or both, Quigley told Reuters Health.

Plus, chronic glaucoma, the most common form of the condition, has few warning signs or symptoms.

"It's easy to forget about any asymptomatic disease that you don't notice until it has already made you blind or already caused you a stroke," Quigley said.

More than 2.2 million Americans are estimated to have glaucoma, which can lead to blindness. The accompanying vision loss cannot be reversed, but can be controlled if the disease is detected early through eye exams.

For the new study, researchers examined a random sample of Medicare claims submitted by ophthalmologists, optometrists and outpatient surgery centers. They looked at seven years of data, from 2002 through 2008, across nine large geographic regions and 179 subregions.

From that data, the researchers concluded that acute glaucoma -- a condition in which eye pressure builds suddenly and quickly -- was seriously underdiagnosed.

The New York City area had the highest rates of the condition of all the 179 subregions, which indicated that physicians there were either overdiagnosing it or doing a better job of detecting it.

The low rates of diagnosis in all the other areas suggest it's the latter, researchers said, and New York is doing a better job at detection.

"Healthcare providers need to be performing gonioscopy on a regular basis," said Sandra Cassard, the study's lead author. Gonioscopy -- an eye exam -- is necessary to diagnose acute glaucoma.

In general, glaucoma rates rose from 10.4 percent in 2002 to 11.9 percent in 2008. Women were more likely than men to have the condition, the study found. And rates of most forms of the condition rose until age 80 then fell thereafter.

"This may indicate lack of continuity in care among the very old," Cassard told Reuters Health. "Seniors need to be encouraged to visit eye-care professionals," especially those over age 80 who may not be making the recommended yearly office visit, she said.

Only about half of the beneficiaries made an office visit to an optometrist or ophthalmologist in 2008.

Blacks, Hispanics and Asians were less likely than non-Hispanic whites to have a vision-care visit, but they also showed the highest rates of glaucoma and greater risk of developing it.

While failure to detect glaucoma early can lead to blindness, over-diagnosis presents its own challenges to physicians, researchers noted.

According to Dr. Shakeel Shareef, an associate professor of ophthalmology at the University of Rochester Medical Center, about 30 percent of his glaucoma referrals turn out not to have the condition.

"But at least the referring doctor did not subject someone to treatment for life on medications" that were unnecessary, he told Reuters Health.

In many cases, patients "don't necessarily need to be treated but they need to be monitored" for risk of developing the condition, said Shareef, who was not involved in the study.